Commander BJ Harrington, who was leading the police operation, said: “Although the vast majority of people left the stadium peacefully and were well behaved, there were a minority of people who attended the match that were clearly intent on being involved in confrontation and violence.

“Despite extensive work with both clubs and the London Stadium partners as well as a large and robust policing operation, there were unacceptable incidents inside and outside the stadium, before, during and after the game.

“We welcome the condemnation from partners and have already started a post-match investigation.

“We have already made seven arrests and will work tirelessly to identify people involved and bring them to justice.”

West Ham and Chelsea made statements soon after the match.

A West Ham statement read: “West Ham United and London Stadium partners unreservedly condemn the behaviour of individuals involved in incidents during this evening’s fixture with Chelsea.

“Whilst quickly brought under control, the club, in line with its clear zero tolerance policy, will work closely with London Stadium 185, the Metropolitan Police Service and Chelsea to identify the individuals involved.

“Once identified, those found to have acted improperly will be banned from attending any West Ham United fixtures for life and we will request the courts serve banning orders to prevent these individuals attending any other football.”

West Ham manager Slaven Bilic described the scenes as “unacceptable” and Chelsea head coach Antonio Conte expressed his disappointment.